1. Field of the Invention
The present invention relates to a system which supports and feeds roll-film in a camera.
2. Description of the Related Art
In photography using light-sensitive film such as 35 mm roll-film or 120 roll-film, a film frame of the roll-film which lies on the pressure plate of the camera (i.e., in the rectangular picture format area of the camera) must be held flat during the exposure of the film frame. However, due to a curling effect of the film, it is sometimes the case that the film frame on the pressure plate cannot be held flat precisely if the film frame is simply fed to lie on the pressure plate. To prevent this problem from occurring, there has been developed a vacuum mechanism which brings the film frame into intimate contact with the pressure plate by vacuum aspiration. Such a conventional vacuum mechanism is provided with a coil as a drive source so that an air suction pump is actuated by electromagnetic force generated by the coil to bring the film frame into intimate contact with the pressure plate by vacuum aspiration. However, according to such a conventional vacuum mechanism, it is necessary to provide a camera with such an independent drive source so as to suck the film frame on the pressure plate, which is disadvantageous in the efficiency of space in the camera and also the cost of production. Furthermore, in such a conventional vacuum mechanism, the duration of film suction is generally short, so that the conventional vacuum mechanism is not suitable for bulb exposure.
The present invention has been devised in view of the aforementioned problems that reside in the conventional vacuum mechanism. An object of the present invention is to provide a film support and feed system of a camera which does not require an independent drive source for bringing the film frame which lies on the pressure plate into intimate contact with the pressure plate by vacuum aspiration, and which makes a long-duration film suction possible with excellent space efficiency and at a low cost of production.
To achieve the object mentioned above, according to an aspect of the present invention, a film support and feed system of a camera is provided, including a pressure plate positioned immediately behind a frame of roll-film which is to be exposed at a shutter release, a film feed mechanism which moves the film frame in a space in front of the pressure plate, a film suction mechanism which brings the film frame into intimate contact with the pressure plate by vacuum aspiration, a reversible motor, and an associating mechanism which selectively associates the reversible motor with either the film feed mechanism or the film suction mechanism in accordance with a direction of rotation of the reversible motor. The reversible motor is associated with the film feed mechanism by the associating mechanism to operate the film feed mechanism when the reversible motor is driven to rotate in a forward direction, and the reversible motor is associated with the film suction mechanism by the association mechanism to operate the film suction mechanism when the reversible motor is driven to rotate in a reverse direction.
With this film support and feed system, the reversible motor used to drive the film feed mechanism is also used to drive the film suction mechanism. Therefore it is unnecessary to provide two independent drive sources (motors) for the film feed mechanism and the film suction mechanism, which is advantageous for space efficiency in the camera, and also lowers the cost of production. Furthermore, since the film suction operation continues as long as the reversible motor is driven to rotate in the reverse direction, the camera body with the film back can be advantageously used for bulb exposure.
Preferably, a controller is also included, which controls the reversible motor to continue rotating in the reverse direction to thereby keep the film frame into intimate contact with the pressure plate by vacuum aspiration by the film suction mechanism during an exposure of the film frame.
Preferably, the associating mechanism includes a planet gear which is engaged with a gear of either the film feed mechanism or the film suction mechanism when the reversible motor is driven to rotate in the forward direction or the reverse direction, respectively.
Preferably, the camera includes a camera body and a film back which is detachably attached to the camera body, wherein at least the pressure plate, the film feed mechanism and the film suction mechanism are incorporated in the film back.
In an embodiment, a film winding operation in which the roll-film is wound on a take-up spool of the camera is performed when the reversible motor is driven to rotate in the forward direction.
Preferably, the film suction mechanism includes a plurality of through holes formed on pressure plate, and a suction pump having a rotor; wherein the suction pump is associated with the reversible motor to rotate the rotor when the reversible motor is driven to rotate in the reverse direction.
In an embodiment, the space, in which the film frame is moved by the film feed mechanism, is positioned behind an aperture formed on the camera body which forms the limits of each film frame exposed of the roll-film.
Preferably, the associating mechanism includes a planetary gear which includes of a sun gear and a planet gear which is engaged with and rotates around the sun gear.
According to another aspect of the present invention, a camera system having a camera body and a film back which is detachably attached to the camera body is provided, the camera body including a reversible motor, wherein roll-film is accommodated in the film back. The film back includes a pressure plate positioned immediately behind a film frame of the roll-film which is to be exposed at a shutter release, a film feed mechanism which feeds the film frame, a film suction mechanism which brings the film frame into intimate contact with the pressure plate by vacuum aspiration, and an associating mechanism which selectively associates the reversible motor with one of the film feed mechanism and the film suction mechanism in accordance with a direction of rotation of the reversible motor. The reversible motor is associated with the film feed mechanism by the associating mechanism to operate the film feed mechanism when the reversible motor is driven to rotate in a forward direction. The reversible motor is associated with the film suction mechanism by the association mechanism to operate the film suction mechanism when the reversible motor is driven to rotate in a reverse direction.
According to another aspect of the present invention, a film support and feed system of a camera is provided, including a film feed mechanism which moves a-roll film in a space in front of a pressure plate, a film suction mechanism which brings the film into intimate contact with the pressure plate by vacuum aspiration, a reversible motor, and an associating mechanism which selectively associates the reversible motor with the film feed mechanism or the film suction mechanism in accordance with a forward rotation or reverse rotation of the reversible motor.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 11-366564 (filed on Dec. 24, 1999) which is expressly incorporated herein by reference in its entirety.